Polyesters light-stabilized with 4-thiazolidone derivatives



United States Patent 2,987,503 POLYESTERS LIGHT-STABILIZEDWITH 4-THIAZOLIDONE DERIVATIVES James A. Van Allan, Rochester, N.Y., and Gerald'R- I .appin and John W. Tamblyn, Kingsport, Tenn.', :18-

slgnors' to Eastman-Kodak'Company, Rochester, N.Y.,

a corporation of New Jersey NoDrawing. Filed Jan. 4, 1957, Ser. No. 632,406 9 Claims. (Cl. 260-75) This invention concerns light-stabilized plastic compositions, more particularly polymeric materials in which the light-stabilizing radical ispart of the polymer molecule.

It has been customary to. stablizeplastic compositions against the deteriorating action of ultraviolet light by incorporating in these compositions alight-stabilizing additiv'e. With relatively thick plastic pieces this practice has been very successful- However, withathin films and fibers, such additives have proved quite ineffective, because they are soon lost by evaporation or leaching or both during exposure. In'these thin sections there isno internal reservoir of stabilizer to keep furnishing the exposed surface with a fresh supply by dilfusion Plastic materials which are made and processed at high temperatures, such as the polyesters, posea particularly difiicult problem-with regard to the successful incorporation oforganic light stabilizers.

We have found that certain thiazolidone derivatives have the requisitethermal stability to survive the high temperatures at which. certain polyesters are made and processed- In addition, we" have' 'discovered"that'when the thiazolidones are attached to the molecule and inserted in the polyester chain that thin films and fibers made from such stabilized polyesters have improvedligh't and weathering stability.

One object of this-invention? is to provide-light stabilizers for polymeric materials. Another object of this invention-is to provide light stabilizers for thin films and fibers-which will not leach out or'evaporate. A further object of this invention is to provide a light stabilizer which may be chemically built into the chain molecule of polyesters: An additional object of this invention is to: provide-alight stabilizer which will withstand the high temperatures at which polyesters are made and processed. Another object is to provide a polyester material which has a light stabilizer polymerized in the polyester.

Inthe' practice of our invention we prepare-derivatives of tliiazolidones'with hior polyfunctionalglycol or acid groupings attachedto the molecule: so that they may be inserted in the polyester chain at any-desiredveoncentration.

lit-our preferred embodimentotthe. invention, -benzal 3 prB-hydroxyethylphenyl-Z-p-B-hydroxyethylphenylimino-4-thiazo'lidone is prepared as follows:

A" mixture 'of'200 grams of Z-p-aminophenyl ethanol, 200 of carbon disulfide and 200 ml. of ethanol was refluxed 70h01'1r8. T P fP Hct separated at the end of this time-in a solid crystalline mass. Excess solvent was removed on the steam bath'an'd theresidue was recrystalperature of-250-260 C. for 12 minutes.

2,987,503 Patented June 6, 1961 lized from methanol-water to. give 56 g. of 3-(pp-hydroxyethylphenyl) 2f- (p-B-hydroxyethylphenylimino) -4- thiazolidone, M.P. 124 C. 8.9 g. of this thiazolidone, 4.0-'ml'. of benzaldehyde, 2 ml. of piperidine and 50 ml. Qfmethanol were mixed and refluxed 5 hours. Water was added to the reaction mixture. An oil,.,which soon solidified, separated. Recrystallization from methanolwater gave 11 g. of the desired product, 5-benzal-3-p-phydroxyethylphenyl 2 p-fi-hydroxyethylphenylimino-4- thiazolidone, MLP. l29l30 C.

'I'he'following examples illustrate the preparation of the stabilized polyesters, but are not intended to 'limitthe scope of our invention:

EXAMPLE 1 A polyester from'25 mole percent p,p-dicarboxydiphen.- ylsulfone, 25 mole percent sebacic acid and 50 mole percentLS-pentanediol containing approximately 5 percent of the bifunctional thiazolidone described above was prepared as follows:

A mixture of 104.5 g. (0:25 mole) of dibutyl-p,p-sulfonyldibenzoate, 78.5.g. (0.25 mole) of dibutyl sebacate, 104 g. (1.0. mole) of 1,5-pentanediol, 10 g. of the stabilizer described above and 1.0 ml. of a solution of 2 percent NaHTi(0C H) was stirred and' heated. The mixturewas heated at atmospheric pressure until no furtherdistfllate came 'over"(about 1 hour) andthevpot temperature-had reached 230: C. Heating was then continued at a pressure. of about 0.2 mm. and apot tem- The hot melt was poured into water. The dried prepolymer was washed with acetone and ground to pass a 20-mesh screen. It was then heated for 3.5 hours at 160-190 C. at a pressure of 0.07 mm. to give 114 g. of pale yellow polymer, inherent viscosity 0.86, at a concn. of 0.25 g./ cc. in 60:40 (by.weight) phenolztetrachloroethane at 25.0" C. which contained approximately 5 percent of the described stabilizer.

EXAMPLE 2 A polyester was prepared from 41.5 mole percent p,p'-dicarboxydiphenyl sulfone, 8.5 mole percent succinic acid'and 50 mole percent 1,5-pentanediol containing approximately-three percent ofthe bifunctional thiazolidone described above as follows:

The polymer was prepared by a method analogousto that of 'Example 1 from 209 g. (0.5 mole) of dibutyl-p;psulfonyldibenzoate, 10 g; (0.1 mole) of succinic anhydride; g. (1.2 mole) of 1,5-pentanediol, 2.1 g. of the stabilizer described above, and'0.7 ml. of 2 percent NaHTi(OC H solution. There'were obtained 1321. of pale yellow polymer, inherent viscosity 1.00; measured as in Example 1, which contained about 3 percent of the the built-in stabilizer;

Thestructural formula for the condensation polymer from dibutylp,p-sulfonyldibenzoate and 5-benzal-3-(pfl-hydroxyethylphenyl) -2- (p-B-hydroxyethylphenylimino) .4-thiazolidone is indicated below:

ethyl) thiocarbanilide, MP; 178' C. 56 g. ofthis prodnot, 24 g. ofchlor'oacetic acid, 24 g. of sodiumacetate and 200 ml. of ethanol weremixed and refluxed overnight. The ethanol was evaporated and water added to the residue' The crystals were-filteredofandrecrystalwhere x=z+y and the ratio. of z to y may be varied widely. M is a glycol residue.

EXAMPLE 3 A polyester was prepared from 37.5 mole percent terephthalic acid, 12.5 mole percent succinic acid and 50 mole percent 1,4-cyclohexanedimethanolcontaining approximately one percent of the bifunctional thiazolidone described above as follows:

A polyester was prepared by a method analogous to Example 1 from 116 g. (0.6 mole) of dimethylterephthalate, 20 g. (0.2 mole) of succinic anhydride, 144 g. (1.0 mole) of 1,4-cyclohexanedimethanol, 2.1 g. of the stabilizer described above, and 0.9 m1. 2 percent NaHTi(OC H solution. There were obtained 165 g. of pale yellow polymer, inherent viscosity 0.75, measured as in Example 1, which contained approximately 1 percent of the subject additive.

' EXAMPLE 4 The polyester described above in Example 1 was meltspun into 3-denier yarn filaments and exposed in a modificd Atlas Twin-Arc Weather-Ometer (Anal. Chem., 25, 460 (1953)). Similar yarn, made from a polyester of the same composition without the built-in thiazolidone was also exposed for comparison. Table I shows the improvement in light stability, as measured by retention of tenacity and elongation during exposure, of the stabilized yarn-over the unstabilized yarn. The rate of '-loss of these physical properties may be seen to be some 25 times slower in the stabilized yarn.

Table I The polyester described above in Example 2 was meltspun into 3-denier fialments and exposed as in Example 4 along with similar yarn made from an unstabilized polyester of the same composition. In addition, a third yarn sample, containing three parts of a similar thiazolidone 5-benzal-3-( o-ethylphenyl) -2- (o-ethylphenylimino- 4-thiazolidone)) simply mixed into but not chemically built into 100 parts of the polyester, was also made and .testcd. The results, given in Table II show that the yarn containing the chemically built-in stabilizer had about ;-l 0 times the weathering resistance of the unstabilized yarn, while the yarn containing the mixed-in stabilizer had only about 4 times the weathering resistance of the unst abilized yarn; Table II Percent 01 Original Exposure Property Retained Yarn Time Tenacity Elongation 0 100 100 6 66 70 Unstabilized 16 30 26 a 24 25 21 40 15 12 0 100 100 8 88 85 Stabilized with 3 parts tliiazoli- 14 75 76 done (mixed in) 24 55 50 40 38 p 39 66 20 v 18 -0 100 L100 .2 "-32 a Stabilized with 3 parts thiazolidone (chemically built in) 2 13a 49- 53 177 49 42 Unstabilized polyester oi terephthalic acid and 0 18 Unstabilized polyester of terephthalic acid, 3%

'cally added stabilizer.

4 EXAMPLE 6 The polyester described abpve in Example 3 was meltspun into 3-denier filaments and exposed as in Example 4 along with similar yarnmade from an unstabilized polyester of the same composition. Yarn made from the polyester of terephthalic acid and ethylene glycol was also made in the unstabilized form and tested for comparison. Table III gives the results. The polyester containing the chemically built-in stabilizer showed about three times as good a weathering resistance as either of the unstabilized polyesters. The inherentstability of the unstabilized polyesters used in this example was much greater than the stability of the unstabilized polyesters used in Examples 4 and 5.

Table III Percent Original Elongation Retained Exposure Yarn Time (HR) esaeeeeethylene glycol suceinie acid and 1,4-cyc1ohexane dimethanol.

Stabilized polyester of terephthalic acid,

suceinic acid and 1,4cyclohexane dimethanol.

eeeeaaaaeaae EXAMPLE 7 The stabilized polyester described in Example 1 was dissolved in tetrachloroethane and cast into a film 3 mils thick. Similar films were made from (a) the corresponding unstabilized polyester and (b) the mixture'of the unstabilized polyester with 5% of the stabilizer 5- benzal-3-p-B-hydroxyethylphenyl 2 p ,8 hydroxyethylphenylimino-4-thiazolidone. In the first film the stabilizer was chemically combined with the polyester. In the third film the stabilizer was simply mechanically mixed These films were exposed as in Example 4 and examined from time to time for signs of developing brittleness. As shown by the data in Table IV the chemically combined stabilizer was much superior to the mechani- Table l V 7 Exposure Time '(hr.)'- Required to Cause Film Break on creasing Cracks on Creasing Unatabilized poly ter mixed v buit These chemically built-in stabilizers may be applied to a great variety of polymeric materials besides polyesters. Cellulose esters, for example, containing stabilizing groupings in place of some of the esters groupings, can be made. 'Vinyl polymers made in the presence of .copolymerizable groupings can also be synthesized.

Other biand polyfunctional derivatives, suchas carboxy, carboalkoxy or amino derivatives, are the scope of our invention and may be employed alternatively tothe di-(p-hydroxyethyl) derivative illustrated infthe hen M 5 above examples. isomeric forms, such aS S-p-Q-hydroXY- ethylbenzal-3-p-fl-hydroxyethylfihenyl-2-phenylimino 4 thiazolidone can also be'used.

The following structural tormulzr-indicates the general configuration operable in our invention.

RN'c=o RN=' o=cH-o.H,

a may be Oo'o'ocun" onto 0 o 02H:

Qomonmm Our preferred emsoaanens' -biiial- 3-( p-p-hydroxyethylphenyl)*2-(p-p-hydroxyethylphenylimino)-4-thiazolidone is represented as follows:

However, the isomer, 5-p-B-hydroxyethylbenzal-3-p-B- hydroxyethylphenyl-Z-phenylimino-4-thiazolidone can also be used. It is represented structurally as follows:

Among the typical polyesters in which these thiazolidones may be incorporated by polymerizing with the monomers are those disclosed in the copending US. patent application Serial No. 554,639, filed December 22, 1955.

The preferred embodiment of our invention is the use of 16% of the built in stabilizer based on the weight of the polymeric material.

We claim:

1. A process for stabilizing a polyester from a dihydric alcohol and a dicarboxylic acid comprising adding 1-6% based on the weight in combined form of the final polymeric material of a 4-thiazolidone having the formula:

RlTIC=O R-N=C 3=CH--C H,

in which R is selected from the class consisting of @o o 0 0,11 @0 omc 0001B @cmonmm and to the polymerizable mixture of terephthalic acid, a dicarboxylic acid having 4-12 carbon atoms and ethylene glycol prior to polymerization, polymerizing the polymerizable mixture under polyesterification conditions, 'an removing the polymer from the mixture.

4. A process for stabilizing a polyester of p,pdicarboxydiphenyl sulfone, pentanediol, and a dicarboxylic acid having 4-12 carbon atoms, comprising adding 1-6% by weight in combined form of the polymer of a 4-thiazolidone having the formula:

and

in which R is selected from the class consisting of @o 0 0 02m @0 onto 0 0 can @omonmm to the polymerizable mixture of p,p'-dicarboxydiphenyl sulfone, pentanediol, and a dicarboxylic acid having 4-12 carbon atoms, polymerizing the polymerizable mixture under polyestcrification conditions, and removing the polymer from the mixture.

5. A polyester from a dihydric alcohol and a dicarboxylic acid containing 1-6% by weight in combined form of the total polymeric mixture of a 4-thiazolidone having the formula:

in which R is selected from the class consisting of @00 0 02m @0 011,000 can.

@omonmm 6. A polyester of terephthalic acid, a dicarboxylic acid having 4-12 carbon atoms, ethylene glycol and 1-6% by weight of the polyester in combined form of 5-benzal-3-pp hydroxyethylphenyl-2-p-fi-hydroxyethylphenylimino 4- thiazolidone.

7. A polyester of p,p'-dicarboxydiphenyl sulfone, a diand carboxylic acid having 4-12 carbon atoms, pentanediol, and 1-6% by weight of the polyester by weight in combined form of 5-benzal-3-p-:hydroxyethylphenyl-Z-p-B- hydrbxyethylphenyliminoA-thiazolidone.

8. A polyester of terephthalic acid, a dicarboxylic acid having 4-12 carbon atoms, ethylene glycol, and 1-6% by weight of the polyester in combined form of a 4-thiazolidone having the formula:

in which R is selected from the class consisting of 9. A polyester of p,p'-dicarboxydiphenyl sulfone, a diand . carboxylic acid having 412 carbon atoms, pentanediol,

8 and 1-6% by weight of the polyester in combined form of a 4-thiazolidone having the formula:

I R'N'C=O R-N= C==CH-C5H5 -V r in which R is selected from the class consisting of and References Cited in the file of this patent UNITED STATES PATENTS 2,352,152 Kaplan June-20',- 1944 2,399,118 Homeyer Apr. 23, 1946 2,680,727 Jarboe June 8, 1954 2,784,087 Sawdey et al. 'M'3I. 5, 1957 25 2,875,053 Minsk Feb. 24, 1959 

1. A PROCESS FOR STABILIZING A POLYESTER FROM A DIHYDRIC ALCOHOL AND A DICARBOXYLIC ACID COMPRISING ADDING 1-6% BASED ON THE WEIGHT IN COMBINED FORM OF THE FINAL POLYMERIC MATERIAL OF A 4-THIAZOLIDONE HAVING THE FORMULA: 